Active sugar transport by the small intestine. The effects of sugars, amino acids, hexosamines, sulfhydryl-reacting compounds, and cations on the preferential binding of D-glucose to tris-disrupted brush borders.
Tris-disrupted and intact brush border membrane preparations from mucosa of hamster jejunum were capable of preferentially binding actively transported D-glucose in a similar manner. Density gradient centrifugation of the Tris-disrupted brush borders indicated that D-glucose was bound to a fraction containing the cores or inner material of the microvilli. The properties of this binding were examined with the Tris-disrupted brush border preparation. Actively transported sugars competitively inhibited preferential D-glucose binding, whereas no effect was observed with nonactively transported sugars. Neither actively nor nonactively transported amino acids affected D-glucose binding. D-Glucosamine, which is not actively transported, was inhibitory to preferential D-glucose binding as well as to the active transport of D-glucose by everted sacs of hamster jejunum. No inhibitory effect was observed with the same concentration of D-galactosamine. Preferential D-glucose binding was also inhibited by sulfhydryl-reacting compounds, Ca(2+), and Li(+) ions. On the other hand, Mg(2+) was shown to be stimulatory and Na(+), NH(4) (+), and K(+) had no effect on this phenomenon. The results of these experiments suggest that preferential D-glucose binding to brush borders is related to the initial step in active sugar transport by the small intestine.
D000596:Amino Acids / Q000494:pharmacology; D000641:Ammonia / Q000494:pharmacology; D001692:Biological Transport; D001693:Biological Transport, Active; D002118:Calcium / Q000494:pharmacology; D002247:Carbon Isotopes; D002499:Centrifugation, Density Gradient; D005690:Galactose / Q000494:pharmacology; D005944:Glucosamine / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism*; D006595:Hexosamines / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000378:metabolism*; D007583:Jejunum / Q000166:cytology; D008094:Lithium / Q000494:pharmacology; D008274:Magnesium / Q000494:pharmacology; D008358:Mannose; D011188:Potassium / Q000494:pharmacology; D012964:Sodium / Q000494:pharmacology; D013438:Sulfhydryl Compounds / Q000494:pharmacology; D014316:Tritium; D014994:Xylose / Q000494:pharmacology
D000596:Amino Acids; D002247:Carbon Isotopes; D006595:Hexosamines; D013438:Sulfhydryl Compounds; D014316:Tritium; D000641:Ammonia; D008094:Lithium; D012964:Sodium; D014994:Xylose; D008274:Magnesium; D005947:Glucose; D005944:Glucosamine; D008358:Mannose; D011188:Potassium; D002118:Calcium; D005690:Galactose